One of the conventional lubricating devices for lubricating an outer ring of the bearing is disclosed in Japanese Unexamined Patent Publication 2004-270876, for example. The conventional lubricating device will be described with reference to FIG. 6.
This conventional lubricating device is fixed to a bearing B. The bearing B comprises a support shaft 1, an inner ring 2 having a diameter greater than that of the support shaft 1 and receiving the support shaft 1 inserted therein, and an outer ring 3 provided around the inner ring 2. A plurality of rollers are rotatably interposed between the inner ring 2 and the outer ring 3 so as to allow for smooth relative rotation of the outer ring 3 to the support shaft 1 and inner ring 2.
The bearing B structured as described above supports the supported item on the outer ring 3 such that the supported item can rotate. For the smooth relative rotation between the outer ring 3 and the supported item, a lubricant is applied to the outer periphery of the outer ring 3 at all times.
A lubricating device 4 is disposed around the outer ring 3 for providing the lubricant. The lubricating device 4 comprises a supporting member 5 of approximately C shaped cross-section, and a lubricating member 6 secured on the inner side of the supporting member 5.
The lubricating member 6 is a resin member impregnated with a lubricant and maintains a dimensional relationship with the supporting member 5 in which the lubricating member 6 is tightly fitted into the supporting member 5. The lubricating member 6 has a recess 6a having the open upper-end. The lubricating device 4 is fixed to the support shaft 1 in such a manner as to surround the outer ring 3 of the bearing B. The outer ring 3 maintains a dimensional relationship with the lubricating device 4 in which a slight clearance 7 is kept in the recess 6a of the lubricating member 6.
In the lubricating member 6, lubricant contact ribs 8 extend out from the recess 6a to make contact at three points between the upper and bottom portions of the outer periphery of the outer ring 3 and the lubricating member 6 for the lubrication of the outer ring 3.
In FIG. 6, contact strips 9 extend upward from the top face of the lubricating member 6, and directly lubricate the supported item which is borne by the outer ring 3.
In this way, when the lubricating device 4 is provided around the outer ring of the bearing B, the outer ring 3 of the bearing B and the supported item borne by the bearing B can be lubricated with a lubricant at all times, thus realizing the smooth relative rotation of the outer ring 3 and the supported item.
Most of the lubricating member 6 of the conventional lubricating device 4 is placed so as to surround approximately the entire periphery of the outer ring 3. However, the effective time-period of the lubricating member 6 during which the lubricating member 6 is capable of lubricating the outer ring 3, that is, the life expectancy of the lubricating member 6, is significantly longer than the service life of the bearing B or the machine using the bearing B. In addition, the lubricant saturating the lubricating member 6 is not completely applied to the outer ring 3. In other words, if the lubricating member 6 is provided approximately around the entire periphery of the outer ring 3, the amount of lubricant contained in the lubricating member 6 is excessive for the outer ring 3. In this way, the manufacturing costs for the conventional lubricating device 4 increase because the lubricating member 6 contains a greater amount of lubricant than necessary.
The lubricating device 4 lubricates the outer ring 3 through the lubricant contact ribs 8. If the contact between the lubricant contact ribs 8 and the outer ring 3 is too weak, the outer ring 3 cannot be adequately lubricated.
The avoidance of this necessitates strict dimension control of the lubricating member 6 during the manufacturing process of the lubricating member 6, so that the outer ring 3 is exactly in contact with each of the lubricant contact ribs 8. Also, a complicated assembly process for fixing the lubricating device to the bearing is necessary.